Improved control method and device for oxygen pump cells of sensors in internal combustion engines or exhaust gas after treatment systems of such engines
a technology of internal combustion engine and pump cell, which is applied in the direction of pump control, measurement device, and positive displacement liquid engine, etc., can solve the problems of unstable sensor signal, heavy disturbance of control loop, and inability to reliably operate sensor signals during transient operation
Active Publication Date: 2012-11-15
FPT MOTORENFORSCHUNG
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[0013]These and further objects are achieved by means of an improved control method and device for Oxygen pump cells of sensors in internal combustion engines or exhaust gas after treatment systems of such engines, as described in the attached claims, which form an integral part of the present description.
Problems solved by technology
During transient operation of the engine, the oxygen content may vary very strongly and quickly, which causes heavy disturbances in the control loops and therewith unstable sensor signals.
Generally, the sensor signals are not reliable during transient operation, especially in the Diesel environment, where the expected variations of the oxygen concentrations are very significant.
In the known sensors therefore the reduced reliability during transient phases makes nonlinear filter techniques necessary, which however may significantly slow down and also disturb the sensor response and therefore the bandwidth of the feedback control loops in the engines.
Method used
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[0022]According to the invention, engine operation data are used in order to improve the performance of the oxygen pump controller. This allows a significant acceleration of the sensor response, which in turn increases the sensor accuracy during transient phases and thus allows the extension of the control loop bandwidth.
[0023]The approximate oxygen partial pressure and / or air / fuel ratio (lambda) are critical quantities both for general engine management and for the after-treatment systems. Therefore, this information is always available in an engine control unit. Since these quantities can be directly calculated from the injected fuel and the current amount of oxygen in the cylinder, it is always available prior to influencing a sensor mounted downstream of the engine cylinder outlet. Therefore, this information can be used to pre-adjust the oxygen pump current by means of a feed-forward controller.
[0024]With such a setup the feedback controller only needs to level out local distur...
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It is described a method for controlling an oxygen pump cell of a sensor in an internal combustion engine or in the exhaust gas after treatment system of such an engine, comprising the step of adding, to a feedback control of the current in the pump cell, a further feed-forward control path estimating an expected oxygen pump current on the basis of characteristics of the exhaust gas composition calculated from engine operation data.
Description
FIELD OF THE INVENTION[0001]The present invention relates to an improved control method and device for Oxygen pump cells of sensors in internal combustion engines or exhaust gas after treatment systems of such engines.DESCRIPTION OF THE PRIOR ART[0002]Combustion engines which have to comply with current and future emission legislations make use of an after-treatment system and / or of an exhaust gas recirculation (EGR) system in order to reduce the NOx emissions below the limits imposed by the law. Both types of systems rely on solid-state oxygen, NOx, and lambda sensors. These sensors contain electrochemical pumps, where oxygen ions are pumped through a solid-state electrolyte cell.[0003]As shown in FIG. 1, a Lambda sensor contains a reference cavity 1 with air and a measurement cavity 2 with exhaust gas. The exhaust gas enters the measurement cavity through a diffusion barrier 3. A pump cell 4, using a solid-state electrolyte, is present between the cavity 2 and the exhaust gas side...
Claims
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Login to View More IPC IPC(8): F04B49/00
CPCG01N27/419G01N27/4065
Inventor AUCKENTHALER, THEOPHIL
Owner FPT MOTORENFORSCHUNG